Explore the vast range of titles available.

Nanoindentation testing using a Berkovich indenter was conducted to explore the relationships among indentation hardness (H), elastic work energy (We), plastic work energy (Wp), and total energy (Wt = We + Wp) for deformation among a wide range of pure metal and alloy samples with different hardness, including iron, steel, austenitic stainless steel (H ≈ 2600–9000 MPa), high purity copper, single-crystal tungsten, and 55Ni–45Ti (mass%) alloy. Similar to previous studies, We/Wt and Wp/Wt showed positive and negative linear relationships with elastic strain resistance (H/Er), respectively, where Er is the reduced Young’s modulus obtained by using the nanoindentation. It is typically considered that Wp has no relationship with We; however, we found that Wp/We correlated well with H/Er for all the studied materials. With increasing H/Er, the curve converged toward Wp/We = 1, because the Gibbs free energy should not become negative when indents remain after the indentation. Moreover, H/Er must be less than or equal to 0.08. Thermodynamic analyses emphasized the physical meaning of hardness obtained by nanoindentation; that is, when Er is identical, harder materials show smaller values of Wp/We than those of softer ones during nanoindentation under the same applied load. This fundamental knowledge will be useful for identifying and developing metallic materials with an adequate balance of elastic and plastic energies depending on the application (such as construction or medical equipment).

The aim is to reduce the elastic deformation of the web and side walls of low-stiffness thin-walled beams when the floating fixture method is used. This paper takes the number and position of fixture points as the optimization variables, establishes a calculation model of elastic deformation, and constructs the objective function of maximum total elastic deformation. An optimized solution utilizing the augmented multiplier method is employed, which forms the basis for the fixture layout optimization method to reduce the elastic deformation of low-stiffness thin-walled beams. A theoretical calculation, simulation analysis, and the fixture layout optimization of total maximum elastic deformation were completed using an aluminum alloy low-stiffness thin-walled beam as an example. The results show that based on the optimized layout, the average relative error between the calculated value and the simulated value of total maximum elastic deformation is 17.43%, and the simulated value of maximum elastic deformation is reduced by 48.49% after optimizing the fixture layout. The measured value is reduced by 0.02 mm on average, and deformation is reduced by 74.07%, which verifies the effectiveness of the floating fixture layout optimization control of machining elastic deformation proposed in this paper.

The disturbance factors such as clearance of kinematic pair, irregular wear and elastic deformation of rods are the main factors leading to decline of performance and accuracy of mechanism. For more accurately predict dynamic behavior, an accurate modeling method of nonlinear dynamic of multi-link mechanism (MLM) under the coupling effect of irregular wear clearance and flexible components was proposed. Wear depth of revolute pair is calculated, the shaft and bearing surfaces are reconstructed, and the wear prediction process is coupled with the flexible multi-body dynamic to obtain a rigid-flexible coupling (RFC) dynamic model containing wearing clearances of multiple revolute pairs. The influence of coupling between irregular wear clearance and elastic deformation of components on dynamics of MLM is studied, and chaos phenomena of this mechanism are discriminated. The influence of different clearance sizes and driving speeds on dynamic response and bifurcation diagram of RFC-Mechanism considering wear clearance is studied. A test platform is built for experimental verification. This paper will provide a systematic and perfect theoretical foundation for the research of nonlinear dynamics of high-precision and high-performance multi-link mechanisms.

At present, the horizontal distance between the surface subsidence boundary and the panel is typically selected as the width of the protection coal pillar with the buried pipeline at the gas–coal integrated mining area (traditional method), which causes abundant coal resources to be unrecoverable. To improve the recovery rate of coal resources, the protective coal pillar of the pipeline is optimally designed. First, the Gaussian function equation of the surface subsidence curve is investigated using the probability integral method (PIM). The elastic deformation limit of the pipeline within the subsidence basin was analysed. Then, the failure probability of the pipeline was calculated by analysing the multifactor indicators that affect it. The elastic deformation limit was modified by considering the time effect of the surface subsidence and the failure probability. Next, by analysing the pipeline deformation in the mining subsidence basins, a novel method for the optimal width of the protective coal pillars with buried pipelines in the thick loose layer undermining is proposed. Meanwhile, the verification method and protection measures for pipeline safety are proposed. Finally, theoretical analysis and engineering examples are used for analysis and verification. The results show that the surface subsidence curve caused by critical mining can be expressed by the Gaussian function when the buried depth/thickness ratio (DTR) of the flat coal seam is greater than 40–60 under thick loose layer. Using Panel 132201 as an example, the prediction method reduced the width of the protected coal pillar by 14 m and increased the panel recovery rate by 3.11% while ensuring the safety of the pipeline. This method effectively promotes coordinated mining between oil–gas and coal resources and provides a reference for the design of pipeline protection coal pillars in gas–coal integrated mining areas. HighlightsA novel method for the optimal width of the protective coal pillars with buried pipelines in the thick loose layer undermining was proposed.Under the premise of considering pipeline safety, this method reduced the width of protective coal pillars and increased the panel recovery rate.The elastic deformation limit was corrected while considering the pipeline failure probability.

In normal cold rolling, the elastic deformation of the strip is typically ignored because of the dominant plastic deformation. However, this neglect may introduce additional errors when the strip is very thin. The aim of this study is to investigate the characteristics of the deformation region and thickness reduction in the asymmetrical rolling of ultra-thin strips. Mathematical models were developed based on the slab method, with consideration of the elastic deformation of the strips, and employed in the simulation calculation. The percentage of the three zones and the thickness reduction were analyzed using the simulation results. An increase in the speed ratio results in an increase in the reduction ratio, which is influenced by parameters, such as front tension, back tension, friction coefficient, and entry thickness. The elastic deformation of the strip reduces the tension and the roll pressure and causes the reduction ratio to decrease. The findings and conclusions of this study may be helpful to the mill operating in the asymmetrical rolling process of ultra-thin strips.

CFRP/metal stacks are widely used in aeronautical field. Drilling such stack composite in single shot is still challenging because of different machining properties between CFRP and metal. Delamination often occurs at the exit of the composite which can affect the strength of the composite components. Elastic deformation of CFRP and metal plate occurs in drilling process and furtherly affects the drilling character and critical delamination conditions. The aim of this paper is to study the delamination during drilling of CFRP/metal stacks with deformation of CFRP and metal plate. Analytical mechanical models are proposed to predict critical thrust force of CFRP in the drilling process for two stacking sequences, respectively. The elastic deformation of CFRP and metal plate and the local deformation of uncut CFRP laminate in the cutting zone are taken into consideration. The values of critical thrust force and the influences of the deformation of CFRP and metal plate on critical thrust force are obtained based on the solutions of the model. A series of punching experiments with accurate remained uncut plies is conducted to verify the rationality of the proposed models. The results indicate that the prediction of the proposed model shows a close correlation with the experiment measurements.

The effect of root canal irrigants on the mechanical properties of dentin is crucial in endodontic treatment planning. While antiseptics such as sodium hypochlorite and EDTA are widely used, their potential to weaken dentin structure remains a concern. Polyhexanide-based formulations may offer a safer alternative. To assess the impact of a polyhexanide-based antiseptic composition, compared to standard irrigants, on the microhardness, Young’s modulus, and elastic deformation energy of dentin. Sixty extracted human teeth were sectioned and polished to prepare dentin samples. Baseline measurements of Vickers microhardness, Young’s modulus, and elastic deformation work were performed using a Microhardness Tester (CSM Instruments, Switzerland) with a Berkovich indenter. Samples were then divided into six groups (n = 10 per group) and exposed to different irrigants (NaCl 0.9%, NaOCl 3%, chlorhexidine 2%, EDTA 17%, and polyhexanide-based solutions—0.1% and 0.2% Lavasept). Post-treatment measurements were performed. Statistical analysis was conducted using non-parametric tests with Bonferroni correction. Sodium hypochlorite (3%) caused the most pronounced reduction in dentin microhardness and mechanical strength, though not always statistically significant. Polyhexanide-based solutions (0.1% and 0.2% Lavasept) showed a milder effect, with statistically significant changes observed only in elastic deformation energy for 0.2% polyhexanide. EDTA treatment led to severe surface destruction, precluding reliable post-treatment measurements. Polyhexanide-based irrigants demonstrated a more favorable impact on dentin mechanical properties compared to traditional irrigants, supporting their potential use in endodontic protocols aimed at preserving dentin integrity.

In the commenced work, we establish some novel results concerning graph contractions in a more generalized setting. Furthermore, we deliver some examples to elaborate and explain the usability of the attained results. By virtue of nontrivial examples, we show our results improve, extend, generalize, and unify several noteworthy results in the existing state-of-art. We adopt computer simulation validating our results. To arouse further interest in the subject and to show its efficacy, we devote this work to recent applications which emphasize primarily the applications for the existence of the solution of various models related to engineering problems viz. fourth-order two-point boundary value problems describing deformations of an elastic beam, ascending motion of a rocket, and a class of integral equations. This approach is entirely new and will open up some new directions in the underlying graph structure.

The wire drawing process is commonly perceived as one of the best studied metal forming processes in almost every aspect; however, when considering elastic deformation, researchers usually focus on the uniaxial tensile forces after the material exits the drawing die and not the elastic deformation region before entering the drawing die, even though it may have a significant impact on the strength parameters and the nature of metal flow inside the drawing die. The aim of this research is to theoretically and experimentally identify the deformation in the elastic region and to further link the shape of this region and the values of stress occurring in it with the geometrical parameters of the drawing process and assess its impact on its strength parameters. In order to achieve the assumed goals, numerical analyses using the finite element method and experimental research on the drawing process in laboratory conditions were carried out using Vickers hardness tests and resistance strain gauges measuring deformation in stationary and non-stationary conditions. The obtained results indicate that the shape and the extent of the region of elastic deformations generated in the material before the plastic deformation region during the drawing process depends on the applied deformation coefficient and stationarity of the process.

In order to improve the hitting performance of badminton rackets, the creep characteristics of their nylon string were explored based on the Maxwell and Kelvin models. Special attention was given to the instantaneous elastic deformation coefficient, the delayed elastic deformation coefficient and the retardation time under different conditions. Based on the experimental results, models with high accuracy were developed for nylon, which can describe the changes in the creep rate at different times, relative humidities and stress levels. They all showed that the creep rate increases rapidly with time and then gradually becomes flat. The highest relative humidity led to the lowest instantaneous elastic deformation coefficient and delayed elastic deformation coefficient, but the highest retardation time for nylon. Finally, as the stress level increased, the instantaneous elastic deformation coefficient, delayed elastic deformation coefficient and retardation time all increased. Thus, to improve the hitting performance of badminton rackets, it is necessary to pay attention to the tension and the air humidity in the environment during use.